The use of an enzyme for decomposing oil and fat, for substituting an acyl group in an ester of a fatty acid and alcohol and in oil & fat (mono-, di- or triglyceride) to produce a new glyceride, is increasing. In particular, when producing oil & fat having a specific functionality, a lipase having a position specificity is used in many cases. In order to recover and reuse the lipase enzyme, an immobilized enzyme can be used.
Many of the immobilized enzymes which are available at present are offered in a dried form such as Lipozyme RM IM®, Lipozyme TL IM® and Novozym 435® which are marketed by Novozymes Co., Ltd. The dry form is used, taking into consideration the inhibition of an enzyme from deactivation during storing and proper handling. However, deactivation of an adsorbed immobilized enzyme is liable to occur at a step where the immobilized enzyme is dried under a reduced pressure, in a vacuum or by heating, and the maximum activity shown during adsorption is not achieved in many cases in actually displaying such activity.
A method has been proposed in which an enzyme is adsorbed and immobilized on a carrier, thereby forming an immobilized enzyme, and then immediately brought into direct contact with a reaction substrate without drying to carry out esterification (Japanese Patent Application Laid-Open No. 166589/2000). According to this method, the reaction is delayed in the first reaction by virtue of the influence of a large amount of moisture contained in the immobilized enzyme, but a high activity can be achieved on and after the second reaction. However, the immobilized enzyme has to be immediately contacted with a reaction substrate, because it is not suitable for storage as an immobilized enzyme. Also proposed is a method in which an immobilized enzyme is dried in contact with a fatty acid derivative to thereby enhance development of its activity (Japanese Patent Application Laid-Open No. 134090/1987). In this method, however, the immobilized enzyme has to be slowly dried, and thus its efficiency is inferior. In addition thereto, it is complicated to set up the conditions thereof, and expensive facilities are required. Accordingly, it is not practical.